I had the same problem.
I removed the motor that drives the brush and at the point where the toothed belt transmits the power to the roller, the screw (which is very small) is not strong enough to hold the plastic cone that goes into the roller.
I then ground a washer (for bicycle spoke nipples) between the gear and the cone and into these teeth so that the two parts can no longer twist when installed.
It works.

Vjjbbk

The brush roller has probably turned "round" at the point where the torque is transferred to the brush roller. This happened to my Triflex after 4 years. The brush roller can be ordered as a new spare part.

Hello RikeD
The rotating brush is broken - what to do?:
Some brushes are connected to the wheels by a small drive belt....
If the belt breaks, the rotating brush will no longer rotate.
In this case, the rotating brush must be replaced - rb.

Best thanks in advance for your question - stay healthy - see you soon.

Greetings from Oberi
René BRIGGEN